ok i don't have DE NANO and forgive me if i am making some foolish assumptions but if you already have a 4 channel ADC on your board, then go ahead fire up quartus, create input pins. if your ADC has 8 bit resolution each pin will have 8 bits in it so write a pin name My_channel_A[7..0] then create second pin name it My_channel_B[7..0] so on. create VHDL module place it on your main bsf project and connect wiring connections from your pin to your module. send a clock into your module and clock your input registers. now compile a project once, and go into pin planner assign pin locations to your pins. you will find locations on de nano reference manual pdf. recompile project. thats all. i don't believe that ADC needs some configurations, by default they start up, and instantly generate digital equivalent of anything that comes into their analog input pins. as i understand it, microcontroller simply helps to boot fpga from your pc. or helps it to execute software processes. it has nothing to do with ADC to FPGA pins. on all development boards FPGA is an independent processor. it can never be a slave of someone. -it enslaves everyone around :D it's a boss that's why it is THE HIGH SPEED FPGA and not some lazy microcontroller.